INCREASING THE OPERATING PROPERTIES OF THE MACHINE PARTS BY THE SURFACE RELIEFS

The article discusses the direction of improving the operational properties of machine parts by applying regular reliefs to the surface/ Purpose - to develop a model, plan and methodology for experimental studies of regular reliefs and create their classification by purpose and methods of obtaining. The object of research - regular reliefs on the surface of machine parts. The hierarchy of the main factors that affect the profile of reliefs formed by triangular grooves is determined. This is the normal penetration force of a linear indenter, hardness and elongation of the experimental material. The optimization parameter is the groove depth. A mathematical model and research plan have been developed 23. The methodology and devices for conducting experiments are determined. These are hydraulic presses, linear indenters, optical microscopes, microhardness testers, test materials, instruments, and measuring instruments. Materials for research: alloyed and stainless steel, gray and malleable cast irons, bronze and brass, aluminum and titanium alloys. Classifications of reliefs according to the methods of obtaining and destination are developed. Production methods are based on cold plastic deformation and cutting. The basic methods for the study are static methods: the introduction of a dividing element with discrete drawing and a single protrusion of the shaped mandrel during reduction. The dependence of the depth and double angle of the relief groove on the normal force is shown. A new method for obtaining the surface of a part, including the alternation of supporting platforms and grooves is proposed. The method is carried out using machining and subsequent deformation pulling. A distinctive feature of the method is the use of an intermediate elastic sleeve. KEYWORDS: REGULAR RELIEF, COLD PLASTIC DEFORMATION, LINEAR INDUCTOR, SURFACE OF PARTS, COATING, MODEL OF FORMATION OF RELIEF.

Combined burnishing of cylindrical billets with a modified hole surface

A refined mathematical model of the burnishing forces of hollow cylindrical billets by a tool with regular microgeometry was obtained using metal-clad lubricants that realize the Garkunov—Kragel’skiy wear-free effect during friction. Keywords burnishing force, regular relief, metal-clad lubricant. [email protected]

APPLICATION OF FINISH-STRENGTHENING PROCESS WITH DIAMOND SMOOTHING FOR BEARING CAPACITY INCREASE OF JOINTS WITH TIGHTNESS

The test results of stress joints with a regular micro-relief with the purpose of the assessment of their operation properties increase at finish-strengthening are shown. Thus, shaft endurance in insertions increases at relief application on the surface of a bush hole. It is explained with the pressure concentration decrease caused by a fit at the expense of the growth of joint contact flexibility. A similar effect is achieved at the creation of an artificial camber of a surface with the purpose of obtaining a characteristic diagram of a con-tact load distribution. The formation of a regular relief on the shaft surface results in, besides strengthening, the insignificant increase of the fatigue strength in joints. The static strength increase in stressed joints with the regular micro-relief is explained by the contact interaction character of an unevenness at a cross as-semblage and by the increase of an actual contact area at mechanical pressing-in. At that at reassemblies it was observed a lesser decrease of their strength. A sharp increase of bearing capacity is typical for the mating at a balance of micro-relief high-step parame-ters on contact surfaces of a shaft and a bush. The results obtained lead to the idea of the creation of joints like threaded or splined joints at transferring an axial load or a rotational moment. At the relief formation at the expense of some metal extrusion in overflows there is a raising of a sur-face “plateau” which is used for tightness increase of loose connections and also for rejects correction during manufacturing parts. In such a way the application of efficient tech-nologies of regular micro-relief coatings along with strengthening increases considerably fatigue and static strength in joints with tightness.